It is so easy to loose track of the big picture when comparing different DW Appliance vendors. Different technologies bring different strengths to the table. In that perspective, in a recent project, I had been working on a list of criteria to make it easy to evaluate vendors.
There is no "One size fits all" and there is no perfect Appliance. Every appliance has its perceived strengths and weaknesses. It is up to the end user to evaluate and identify as to which Appliance will fit the needs adequately.
From what I have seen, it is a combination of many factors responsible for a successful and stable deployment.
I hope this selection criteria will be useful for others too. The presentation can be downloaded from here.
DW Appliance - Evaluation Criteria